Question: What do the following two equations represent? $5x+2y = -4$ $-5x-2y = 4$
Answer: Putting the first equation in $y = mx + b$ form gives: $5x+2y = -4$ $2y = -5x-4$ $y = -\dfrac{5}{2}x - 2$ Putting the second equation in $y = mx + b$ form gives: $-5x-2y = 4$ $-2y = 5x+4$ $y = -\dfrac{5}{2}x - 2$ The above equations turn into the same equation, so they represent equal lines.